Upgrade sample to Atmosphere 2.4.14

Closes gh-10447

Author: jfarcand

spring-boot-samples/spring-boot-sample-atmosphere/pom.xml

@@ -32,12 +32,12 @@
 		<dependency>
 			<groupId>org.atmosphere</groupId>
 			<artifactId>atmosphere-runtime</artifactId>
-			<version>2.2.4</version>
+			<version>2.4.14</version>
 		</dependency>
 		<dependency>
 			<groupId>org.webjars</groupId>
 			<artifactId>atmosphere-javascript</artifactId>
-			<version>2.2.3</version>
+			<version>2.3.4</version>
 		</dependency>
 		<!-- Test -->
 		<dependency>

spring-boot-samples/spring-boot-sample-atmosphere/src/main/java/sample/atmosphere/SampleAtmosphereApplication.java

@@ -21,8 +21,8 @@
 import javax.servlet.ServletContext;
 import javax.servlet.ServletException;
 
-import org.atmosphere.cpr.AtmosphereInitializer;
 import org.atmosphere.cpr.AtmosphereServlet;
+import org.atmosphere.cpr.ContainerInitializer;
 
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.SpringBootConfiguration;
@@ -69,7 +69,7 @@ public void addViewControllers(ViewControllerRegistry registry) {
 
 	}
 
-	private static class EmbeddedAtmosphereInitializer extends AtmosphereInitializer
+	private static class EmbeddedAtmosphereInitializer extends ContainerInitializer
 			implements ServletContextInitializer {
 
 		@Override